Glucocorticoids such as cortisone cause cleft palate in fetal mice when pregnant females are treated. A glucocorticoid receptor is thought to play an important role in this process. Our goal is to purify a glucocorticoid receptor which will then be used to elicit a specific antibody. This antibody will be tested for its ability to react specifically with the receptor in fetal mouse tissue. This antibody will enable us to determine how much receptor is present in specific tissues, and how this might vary between mouse strains which have different susceptibilities to cleft palate caused by glucocorticoids. The bulk of our effort in this grant period will be directed toward obtaining purified receptor which can be used as an antigen. We are testing several sources of starting material for this purpose, and we are evaluating various affinity chromatography techniques to determine which might give the best yield of receptor.